The present invention relates to stop angle controller for a vibrato mechanism on a vibraphone.
In general, a vibraphone includes a number of sound boards, each adjusted for a prescribed resonance frequency, which are juxtaposed on a base plate in the order of tonal pitch. Tones are generated by striking the sound boards by means of a mallet or mallets. Each sound board is accompanied with a resonator tube arranged beneath the bottom face of the sound board. Resonance of the air column in the resonator tube increases volume of the tone generated by the associated sound board. Further the resonance enriches sounds in the bass range thereby enlarging the tone range.
Being different from marimbas and xylophones, a vibraphone is equipped with a vibrato mechanism arranged near the top openings of the resonator tubes. More specifically, the vibrato mechanism includes a plurality of fans mounted to a common fan shaft which is coupled to a given drive source via a suitable power transmission. Each fan is located facing the top opening of each resonance tube. When the drive source is activated, the fans are driven for common rotation whereby vibrato performance is available.
At transition from vibrato to non-vibrato performance, the drive source is manually deactivated, but the fans continue to rotate due to inertia and, in general, stop at uncontrolled stop angle. In other words, the stop angle varies from transition to transition. The resonator tubes may be left open, half closed or fully closed depending on the condition of performance and/or the vibraphone at the moment of transition. Thus, no constant tone volume is expected for non-vibrator performance and, as a consequence, no constant performance effect can be expected.